NATURAL SCIENCES OF PHILADELPHIA. 101 



The internal structure of the polyps including that of the stems, bears a re- 

 semblance to that of Pedicellina, and will be more particularly described in u 

 memoir preparing on the animal. 



The youngest independent polyp stems of Urnatella consist of a simple 

 cylindrical pedicle starting from the disk of attachment to the rock, and sup- 

 porting a single polyp head. The pedicle elongates and divides into two seg- 

 ments. The ultimate segment grows in length and again divides; and in this 

 manner all the segments are produced. After the production of three seg- 

 ments, the antepenultimate segment assumes the urn form. Budding com- 

 mences from the second and third segments after their production, and from 

 the succeeding segments, but not usually from the first segment. The buds 

 originate from opposite sides of the base of the segments, aud form branches 

 of a single segment with a polyp head. The pedicle of these branches also 

 frequently gives off a bud, which forms a secondary branch of the same kind 

 as the primary ones. 



In the longer Urnatella stocks, branches are usually observed only from the 

 one two or three terminal segments. In the posterior urn-shaped segments, 

 in the position in which branches emanate in the terminal segments, cup- 

 shaped processes are observed. These were formerly mistaken for buds, hut 

 evidently result from the dehiscence or separation of branches, which leave 

 the parent stock to establish colonies elsewhere. Though I have not observed 

 this separation take place in Urnatella, yet all the points of structure appear 

 to indicate that it actually takes place in the manner intimated. 



It thus appears that the first step towards the multiplication of Urnatella 

 is the segmentation of its stem. The segments put forth buds which develop 

 polyps, and these then separate from the parent stock to settle elsewhere, and 

 become the source of other series of polyps. 



The ultimate history of the segmented polyp stock of Urnatella 1 have not 

 ascertained. The stocks which I have preserved in an aquarium for several 

 months finally lose their terminal polyps. Late in the season, also, all the 

 polyp stocks which I could obtain on the river shore within the reach of my 

 arm, at low tide, were deprived of their terminal folyps. The destruction of 

 these, however, I have suspected to have been due to their having been un- 

 covered in lower tides earlier in the season. I hope yet to be able to deter- 

 mine this question in the course of the next few weeks. 



It has occurred to me that the segmented stems of Urnatella after the derm 

 of the polyps, remained through the winter with little obvious change, and 

 that in the following season, the segments served as reproductive bodies, in 

 the same manner as the statoblasts in Plumatellidae and their allies. This 

 view is, however, not confirmed by specimens retained in the aquarium, and 

 those collected on the edge of the river which had lost their polyps. 



In relation to the production of ova, or the reproduction of Urnatella 

 through sexual agency I have vet learned nothing. 



Among the animals mentioned, as found in association with Urnatella, is 

 the singular Annelide, Manayunkia speciosa, discovered by me some years ago, 

 (Proc A N S 1858, 90.) The worm is closely allied to the marine genus 

 Fabricia, and like it, lives in tubes constructed of mud. It is abundant m the 

 localitv indicated. Individuals of about two lines in length, are usually seen in 

 a state'of division near the middle into two The anterior division of the body 

 consists of five bristle-bearing annul! in addition to the head The posterior 

 division consists of six bristle-bearing annuli in addition to the partially de- 

 veloped head. The anterior head is provided with about thirty-six ciliated 

 tentacnli supported on four lobes. It is also furnished with a pair of ^ : 

 besides which the tentacle-bearing lobes exhibit a number o pigmentary 

 spots, apparently of the nature of eyes. No eyes exist in the tail of Mana- 

 yunkia they do in Fabricia. The blood is green and is pumped intermit- 

 tently into a large vessel occupying one tentacle on each side of the middle 

 of the head. 



1870.J 



